Supporting device for fractured tubular bones

ABSTRACT

An elongated supporting sleeve is to be introduced into a longitudinally extending curved interior cavity of a fractured tubular bone. It is curved in at least substantial conformance with the curvature of the bone cavity and has an internal passage extending longitudinally and through which an expander rod of similar curvature extends. At the front end of the supporting sleeve is located an expansion element which, when the expander rod is withdrawn in axially rearward direction through the passage of the supporting sleeve, is expanded into engagement with the inner walls bounding the bone cavity. An instrumentality is provided for so withdrawing the expander rod that it will perform only a rearward axial movement but will not turn.

Fischer et a1.

SUPPORTING DEVICE FOR F RACTURED TUBULAR BONES Inventors: Artur Fischer, Altheimer Strasse 219, Tumlingen, Germany; Jean-Nicolas Muller, Strassbourg, France said Fischer, by said Muller, Tumlingen, Germany Filed: Feb. 18, 1972 Appl. No.: 227,371

Assignee:

Foreign Application Priority Data Feb. 26, 1971 Germany P 21 09 162.3 Mar. 30, 1971 Germany P 21 15 189.6 Apr. 23, 1971 Germany P 21 19 902.0

US. Cl 128/92 BC, 85/77 Int. Cl. A611 5/04 Field of Search 128/92 BC, 92 BB,

128/92 CA, 92 B, 92 D, 92 R; 85/77, 84, 76

References Cited UNITED STATES PATENTS ilk IIIIIII Sept. 25, 1973 2,243,717 5/1941 Moreira 128/92 BBv 2,121,193 6/1938 Hanicke..... 128/92 BB 3,332,312 7/1967 Bixby 85/84 3,254,555 6/1966 .loneikis 85/77 3,512,448 5/1970 Summerlin et a1 85/77 FOREIGN PATENTS OR APPLICATIONS 453,570 6/1968 Switzerland 128/92 BC Primary ExaminerRicha'rd A. Gaudet Assistant ExaminerJ. Yasko Attorney-Michael S. Striker [57] ABSTRACT An elongated supporting sleeve is to be introduced into a longitudinally extending curved interior cavity of a fractured tubular bone. It is curved in at least substantial conformance with the curvature of the bone cavity and has an internal passage extending longitudinally and through which an expander rod of similar curvature extends. At the front end of the supporting sleeve is located an expansion element which, when the expander rod is withdrawn' in axially rearward direction through the passage of the supporting sleeve. is expanded into engagement with the inner walls bounding the bone cavity. An instrumentality is provided for so withdrawing the expander rod that it will perform only a rearward axial movement but will not turn.

12 Claims, 3 Drawing Figures PATENTED SEPZ 5 I973 SHEEI 2 0F 3 PAIENTEI] SEP25 I973.

sums Bf 3 SUPPORTING DEVICE FOR FRACTURED TUBULAR BONES BACKGROUND or THE INVENTION The present invention relates generally to a supporting device for fractured bones, and more particularly to a supporting device for fractured tubular bones having a longitudinally extending curved interior cavity.

Devices for supporting and connecting fractured bones are already known. It is, in fact, known to use expansion devices for such purposes which are inserted into the bone urging the fracture internally of the bone and connecting the bone fragments together. However, such expansion devices heretofore have not been usable for fractured tubular bones for reasons which are well known to those conversant with this field. Heretofore fractures in tubular bones having a longitudinally extending curved marrow-containing cavity have been repaired by means of pins driven into the marrow-filled interior cavity. The purpose is to provide for lateral securing and also to hold together the fragments of the broken tubular bone. However, the marrow cavity in tubular bones invariably has a contour which converges and then diverges in longitudinal direction of the bone, and as a result a longitudinally driven pin will contact the interior wall bounding the bone cavity only over a small region. The result is that the lateral securing effeet, and the retention of the bone fragments, afforded by such a pin is at best marginal. It has also been proposed to enlarge the contact surface by drilling open the bone marrow cavity, that is to enlarge its diameter at the narrower points in order to obtain a greater surface area and being able to use larger pins. This approach has actually been put into use but with the unfortunate result that infections occurred which in some cases resulted in wasting-away of the bone in question.

A second approach to the problem of repairing fractures in tubular bones has been to use a pin which is curved in conformity with the curvature of the interior wall of the bone marrow cavity. This does, in fact, improve lateral retention of the bone fragments to some extent, but the fragments are not prevented from relative longitudinal displacement because there is no way in which they can be drawn together and held together and held together against relative longitudinal movement. This second approach suffers from still another disadvantage, in that although the lateral retention of the bone fragments is somewhat improved, it is by no means as good as it is desired to be. The reason for this is that the pin is not fixed in that part of the bone marrow cavity which is the divergent part, so that the pin can either turn or become displaced in longitudinal direction when a load is applied to the bone in question.

It is clear, therefore, that the present state of the art of devices for supporting fractured tubular bones laterally and longitudinally is not satisfactory and that improvements are higher desirable.

SUMMARY OF THE INVENTION It is a general object of the present invention to provide such improvements.

More particularly it is an object of the invention to provide'an improved supporting device for fractured tubular bones which is not possessed of the disadvantages outlined above with respect to the prior art, and which affords the improvements which have been set forth above as being desirable.

A concomitant object of the invention is to provide such a supporting device which has a large contact area with the surface bounding the bone marrow cavity of a fractured tubular bone, a contact area which if possible should extend over the entire length or substantially the entire length of the bone.

An additional object of the invention is to provide such a supporting device which affords anchoring of the device in the bone marrow cavity of a fractured tubular bone, and in particular in the divergent portion of the cavity.

Still an additional object of the invention is to provide such a device which is capable of retaining the bone fragments against movement relative to one another in longitudinal direction.

In pursuance of these objects, and of others which will become apparent hereafter, one feature of the invention resides in a supporting device for fractured tubular bones having a longitudinally extending curved interior cavity. Briefly stated, such a supporting device may comprise an elongated supporting sleeve having a leading and a trailing end portion and being curved in at least substantial conformance with the cavity of the fractured bone. The sleeve is provided with a curved longitudinal passage having a widened section at the trailing end portion. An expansion element is located at the leading end portion forwardly thereof, and expander means is associated with the expansion element. This expander means includes rod-shaped means extending through the passage of the sleeve between the end portions thereof and being adapted to expand the expander element in response to axial displacement towards the trailing end. The expander means further comprises displacing means at least partially received in the widened section of the longitudinal passage of the sleeve, being in engagement with the rod-shaped means and being operative for effecting displacement thereof only axially of the sleeve in direction towards the trailing end portion of the latter. Thus, no rotation of the rod-shaped means is necessary or possible.

Tubular bones have a portion which hereafter will be identified as bulge. In order to permit insertion of the supporting device according to the present invention, a hole is drilled into the tubular bone in question at the bulge or in the region thereof, so as to permit access to the interior bone marrow cavity. The supporting device is now inserted through this hole into the bone marrow cavity until the expander element of the device is located in the divergent portion of the cavity, that is the portion which follows the convergent portion and the narrow juncture at the end of the convergent portion. When the device is so positioned, and it must be kept in mind here that the device is bent in conformity with the curvature of the bone marrow cavity of the bone itself, the displacing means is utilized to rearwardly displace the rod-shaped means in a sense causing the expander element to become expanded and thus to be anchored in the bone marrow cavity.

The displacing means is in form of a sleeve-shaped element which advantageously is made so long that the rearward axial displacement of the rod-shaped means does not cause the trailing end of the rod-shaped means to move out of the sleeve-shaped displacing means, so that this rearward end is and remains concealed therewithin. This is advantageous because the development of a pressure point or position, resulting from extending of the rearward end of the rod-shaped means out beyond the sleeve-shaped displacing means, is thereby avoided. This could lead to maximum stress upon the bone when a load is placed on the latter, due to the diameter of the rod-shaped means which is, of course, much smaller than that of the sleeve-shaped displacing means surrounding it.

As has been pointed out before, the supporting device is curved in at least substantial conformance with the curvature of the bone marrow cavity. This means that when it is inserted it is in contact with the interior wall bounding the cavity over a larger region than was heretofore possible. The fractured tubular bone is thereby laterally secured against relative displacement of the bone fragments to an extent not previously achieved, and callus may thus be formed in the shortest possible time at the fracture line, resulting in reconnection of the bone fragments with one another. lt has been found that using the supporting device according to the present invention, the duration of hospitalization or other medical attention required in the case of a fractured tubular bone is substantially reduced over that required where a similar fracture is repaired with one of the pins according to the prior art. Furthermore, the fact that the device according to the present invention can be anchored by expansion of the expansion element also assures that stress can be transmitted to the fractured tubular bone much earlier than was heretofore possible.

In addition, the anchoring of the device via the expansion element thereof eliminates the need for the additional use of wires or of pins driven in from the side of the bone to secure the support element against shifting or twisting in the bone marrow cavity, because such shifting or twisting is reliably precluded.

The list of advantages obtained with the present supporting device is not, however, exhausted with what has been set forth above. Thus it is pointed out that the supporting device may be so constructed as to prevent the bone fragments from performing relative movements in longitudinal direction of the bone. Normally a certain amount of retention of the bone fragments against such longitudinal movement is provided by sinues and muscles surrounding the bone. However, in many cases this is not sufficient, a condition which is especially true when the sinues and muscles are themselves affected by the fracture. The supporting device according to the present invention may be so constructed as to draw the bone fragments axially together and maintain them held together, so that they can be pressed into tight abutment at the fracture and be held in this position.

It is advantageous if the rod-shaped means, for instance a rod which is threaded over part or all of its length on the exterior, has a diameter which is considerably smaller than the diameter of the interior longitudinal passage in the supporting sleeve itself. This means that the rod can be received in this passage with clearance and the difference in the diameters between the rod and the passage will prevent tilting and jamming of the rod in the passage during the expansion of the expander element.

The expander element, incidentally, is advantageously made so that it can be connected with and disconnected from the supporting sleeve, advantageously by means of cooperating screw threads. Some or all of the components of the supporting device may be constructed of V2A or V4A steel i.e. X12CRNI188 or XSCRNIMOISIO, that is steel which can be worked only with difiiculty with cutting tools and which is acid and corrosion resistant. The sleeve and the expansion element can be produced separately and can be made connectable with one another, and one advantage of this is the fact that the bore or passage which must be provided in the interior of the supporting sleeve can now be shortened by the length of the expansion element itself, meaning that shorter and more stable drills may be used in forming the bore.

Still another advantage of making the expansion element and supporting sleeve separate and releasably connectable comes from the fact that the stocking requirements for the components become simplified. This means that it is now only necessary to have a stock of the supporting sleeve on hand in various lengths, whereas the expansion element can always be of one and the same type and dimension (only one type of expansion element need be kept in stock).and can be connected to a supporting sleeve of requisite length when a device is required.

The invention also contemplates an embodiment wherein the threaded rod may be of such a length that it extends beyond the sleeve-shaped displacing means after it has been withdrawn rearwardly to the extent necessary to effect expansion of the expansion element. Thus, a portion of the threaded rod will then extend rearwardly out of the sleeve-shaped displacing means and a cap nut may be threaded onto this portion, being supported against the bone in order to draw the bone fragments together. This embodiment also permits the longitudinal pressing together and holding together of the bone fragments, independently of the anchoring of the device in the bone. I

Another advantageous embodiment of the invention proposes that an extension may be releasably attached to that portion of the threaded rod which extends rearwardly beyond the sleeve-shaped displacing means when the rod has been retracted to the extent necessary to effect expansion of the expansion element. The exterior diameter of this extension should be smaller than the root diameter of the exterior thread of the threaded rod, so that it can be threaded into an axial taped bore provided in the trailing end of the threaded rod. Providing of this threaded extension offers the surgeon the possibility of completely inserting the threaded rod itself without any difficulty into the bone marrow cavity, because he has the extension available for engaging purposes. In addition, the somewhat smaller exterior diameter of the extension as opposed to the root diameter of the threads on the threaded rod, means that the various components which are to be placed over or onto the trailing end of the threaded rod such as for instance the sleeve-shaped displacing means can be readily slipped over the extension and put in place. Thus the extension facilitates the fitting of the device according to the present invention into the bone, and shortens the time required for the operation because the surgeon is relieved of the necessity for having to look into the hole drilled in the bone in order to find the beginning of the screw thread and the trailing end of the threaded rod, where onto to thread for instance the sleeve-shaped displacing means.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 illustrates one embodiment of the invention in an axial section through a fractured tubular bone;

FIG. 2 is a fragmentary detail view, partly sectioned, illustrating a further embodiment of the invention; and

FIG. 3 is a view similar to FIG. 2 but illustrating still another embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing the drawing in detail, and firstly the embodiment illustrated in FIG. I, it will be seen that in this embodiment the supporting device according to the present invention is identified with reference numeral 1 in toto and its various components advantageously, although not necessarily, may be made of V2A or V4A steel. The device I has an elongated supporting sleeve 2 which is curved in at least substantial conformance with the curvature of a longitudinally extending bone marrow cavity which is inherently present in all tubular bones. The bone is shown as being fractured twice, thus being composed of the bone fragments 12a, 12b and 12c, with the two fracture lines being indicated with reference numeral 13.

Secured releasably to the leading end portion of the sleeve 2, which for this purpose is provided with an internal thread 17, is an expansion element 3 whose construction is shown in FIG. 1. An elongated rod 5 is provided for expanding the expansion element 3, carrying at its front end an expander portion 6 which, when the rod 5 is moved axially rearwardly, is drawn between the shanks 15 into which the expansion element 3 is subdivided by a plurality of axially extending slots, and which are spread radially in response to such rearward movement of the rod 5 and the portion 6. The expansion element 3 is provided with an exterior screw thread 16 which meshes with the interior screwthread 17 of the sleeve 2.

The rearward axial displacement of the rod 5 is effectedin this embodiment by means of a sleeve-shaped displacing element 4 which is internally threaded and at least in part received and guided in a widened portion 7 of the longitudinal passage of the sleeve 2 at the trailing end of the latter. The element 4 can abut against and be supported either by the shoulder 8 or the rearward end face of the sleeve 2 itself.

Theaxial length of the element 4 is so selected that when it has been rotated in a sense withdrawing the rod 5 whose exterior screwthreads mesh with the interior screwthreads of the element 4, in axially rearward direction, and when the rod 5 has been rearwardly withdrawn to the extent necessary to fully expand the expansion element 3, there will still be sufficient room left in the interior passage of the element 4 to permit a cap screw 9 to be threaded into the open rear end of the element 4 as shown. In the embodiment of FIG. I the head 10 of the screw 9 bears via a washer l1 -provided to further increase the surface area of contact -against the bone fragment 12a, so that after the expansion element 3 has been expanded and anchored in the portion of the marrow cavity located in the bone fragment 120, the three bone fragments 12a, 12b and 12c can be drawn axially together by means of the screw 9,

thus permitting the bone fragments to be tightly abutted at the fracture lines 13.

Clamping and tilting of the rod 5 in the bore of the sleeve 2 during the rearward axial withdrawing of the rod 5 is prevented by providing rotation-preventing portions 14 on the expanding portion 6 which extend into the slots subdividing the element 3 into the shanks 15, so that the portion 6 and therefore the rod 5 with which it is fast, are prevented from turning.

It is of course evident from FIG. 1 that the device I is curved in accordance with or in at least substantial conformance with the curvature of the bone marrow cavity 18 in the bone 12a, 12b and 12, so that it will contact the inner surface 19 bounding the cavity 18, over a wide range. The lateral fixation of the bone fragments with reference to one another which can beobtained in this manner with the device according to the present invention is excellent and far better than heretofore obtained.

In the embodiment of FIG. 2 like reference numerals designate like elements as in the embodiment of FIG. I. Here only a single bone fragment 12 is shown, and only a portion of the device 1, it being understood that the remainder of the device 1 which is not illustrated corresponds to that portion which has been shown in FIG. 1.

In the embodim entof FIG. 2 the element 4 is of a somewhat different configuration and shorter than the element 4 shown in 1, being threaded onto the trailing end portion of the rod 5 and abutting against the end face of the sleeve 2. In order to in particular facilitate the positioning and threading of the element 4 onto the rod 5, but also to facilitate insertion of the rod 5 itself, a rod-shaped extension 25 is provided whose outer diameter is smaller than the root diameter of the exterior threads 33 on the rod 5. The latter is provided for this purpose with an axially extending tapped bore in its rear free end, this bore being identified with reference numeral 26 and the extension 25 being removably threadable into the tapped bore 26. The element 4 is then simply slipped over the extension 25 until the thread 33 of the rod 5 is reached at which point the element 4 is then turned in a sense threading it onto the thread 33. Such threading, and in particular tightening of the element 4 in a sense rearwardly displacing the rod 5 in order to expand the expansion element 3 (FIG.

1) is effected with a wrench of the Allen type which must, however, have a central bore through which the extension 25 can pass. As in the embodiment of FIG. 1, when the element 4 is tightened the rod 5 will perform movement only in one direction, namely in axially rearward direction to thereby cause expansion of the expansion element 3.

In the embodiment of FIG. 2 the length of the rod 5 has been so chosen that when it has been withdrawn to the maximum extent necessary to issue a proper expansion of the element 3, the rear portion of the rod 5 will I extend rearwardly beyond the element 4. Onto the thus order to gain access to the interior cavity. They are bent at the edges 54 bounding this hole in the manner necessary to overlie the exterior of the bone as illustrated, and they serve to hold in conjunction with the head 51 of the nut 50- the washer 52 in a position in which it extends almost at right angles to the elongation of the sleeve 2, covering at least a part of the opening drilled for access to the interior of the bone cavity. When this has been accomplished, the extension 25 is removed, for which reason it has been illustrated in broken lines in FIG. 2.

It is also advantageous, particularly where the device is to be used for repairing a fractured tubular leg bone, in which case the device must be inserted on the front side of the bone which extends almost parallel with the elongation of the leg, to support the cap nut with a sleeve which can be attached to the end of the supporting device opposite the insertion and, that is the trailing end, and which is secured against twisting in relation to the supporting device and can be retained against the bone by means of an attached hook-shaped lug that can be hooked onto an edge bounding the hole which has been provided in the bone for insertion of the device.

With such a construction, and when the bone fragments are drawn together, the lug will take up the axial forces acting in longitudinal direction of the device while the torque produced by the unilateral support of the sleeve is absorbed by the contact of the sleeve with the interior wall bounding the bone marrow cavity. The length chosen for the sleeve depends on the magnitude of the torque loading to be expected, and in order to keep the surface portion of the sleeve against the interior wall bounding the marrow cavity as small as possible, a long sleeve should'be used when the torque is large, and a short sleeve when the torque is small.

The space requirement for such a sleeve is very small since only one lug attached to this sleeve need be hooked onto an edge of the opening provided in the bone, in order to obtain proper support of the latter. Furthermore, the sleeve can take up great loads because a very good torque absorption is achieved, due to favorable lever relationships and the contact of the sleeve with the interior wall bounding the marrow cavity. In this construction the sleeve is secured against twisting relative to the bone by hooking the lug onto the edge of the opening through which the device is inserted,and it is only necessary to secure the element against twisting in relation to the sleeve and thus to the bone.

The sleeve of a device which is provided with fins preventing twisting, such fins being located at the trailing end, may be provided with slots which extend from the front end in longitudinal direction of the sleeve and wherein the fins are guided. The device is thus secured against twisting relative to the sleeve which in turn is secured against twisting relative to the bone by the lug hooked into the access opening in the bone.

An additional sleeve may also be inserted into the rear end of the first-mentioned sleeve, namely the sleeve supporting the cap nut, and this additional sleeve may contain a flange covering the front face of the firstmentioned sleeve arid serves for enlargement of the contact area with the cap nut, thus assuring that the surface pressure between cap and cap nut and the front face of the sleeve is not unduly large.

The hook-shaped lug may also be provided at this additional sleeve instead of at the first-mentioned one, an

arrangement which has the advantage that the longer sleeve which can be pushed over the rear end of the device may be manufactured from a single tube. Because the device is predominantly produced from V2A or V4A steel, in accordance with a currently preferred concept, it is simpler and less expensive from a manufacturing point of view to provide the hook-shaped lug at the shorter additional sleeve which is provided with a flange for improving the contact surface.

Such an embodiment is illustrated in FIG. 3 wherein again like reference numerals designate like components as in the preceding Figures. A single bone fragment 12 is again shown, and it will be seen that the element 4 is threaded onto the trailing end of the expander rod 5. All such portions of the device 1 which have not been shown in FIG. 3 are identical with the ones which have been shown in FIG. 1.

In the embodiment of FIG. 3 a further sleeve is pushed over the trailing end of the device 1 and is provided with a hook-shaped lug 62 (which may also be provided on a further sleeve 61) which is hooked over an edge 54 bounding the access opening drilled into the bone in order to insert the device 1. Threaded onto that portion of the rod 5 which extends rearwardly beyond the element 4 is a cap nut 50 which again serves to draw the bone fragments together, and whose head 51 abuts either against the end face of the sleeve 60 or against the portion 63 of the additional sleeve 61, which portion 63 overlies the end face of the sleeve 60. The sleeve 61 can be pushed into the rear end of the sleeve 60, as illustrated.

The sleeve 60 is prevented from rotation with respect to the device 1 by being formed with longitudinal slots 64 extending rearwardly from its front end, and into which ribs or fins 65 of the element 1 extend to prevent relative rotation.

When the device has been installed the bone fragments (only the fragment 12 being shown) are drawn axially together by the head of the nut 50, and pressed together until tied abutment is achieved at thefracture lines (compare FIG. 1) so that callus can form which will reunite the fragments.

The device 1 is inserted deeply enough into the cavity of the bone, and anchored therein, to assure that after it is completely installed neither the nut 50 nor the rod 5 extend outwardly beyond the access opening drilled in the bone, thereby assuring that no pressure points can develop which might cause difficulty or damage.

Of course, the device I will ordinarily be removed when the bone fracture is healed, and for this purpose an internal thread 66 may be provided into which a screw, a bolt or an extracting device can be threaded by means of which the device 1 can be withdrawn from the bone cavity when the time to do so has come.

It willbe understood that each of the elements described above, or two or more together, may also find a useful application in other types of construction differing from the types described above.

While the invention has been illustrated and described as embodied in a supporting device for fractured tubular bones, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. A supporting device for fractured tubular bones which have a longitudinally extending curved interior cavity, comprising an elongated supporting sleeve having a leading and a trailing end portion and being curved in at least substantial conformance with said cavity, said supporting sleeve being provided with a curved longitudinal passage having a widened section at said trailing end portion; an expansion element at said leading end portion located forwardly thereof; expander means associated with said expansion element, said expander means including rod-shaped means extending through said passage between said end portions and adapted to expand said element in response to axial displacement towards said trailing end portion, and displacing means at least partially received in said widened section in engagement with said rod-shaped means and operative for effecting displacement thereof only axially of said supporting sleeve in direction towards said trailing end portion, said displacing means being a hollow internally threaded cap sleeve having an open end facing away from said leading end portion, and said rod-shaped means having external screw threads which mesh with the internal threads of said cap sleeve; and a cap screw having external threads dimensioned to mesh with the internal threads of said cap sleeve.

2. A supporting device as defined in claims 1, said expander means further comprising an expander portion provided on said rod-shaped means and engaging said expansion element for effecting expansion of the same in response to said axial displacement of said rodshaped means in direction towards said trailing end portion.

3. A supporting device as defined in claim 1, said rodshaped means having an outer diameter which is substantially smaller than the inner diameter of said passage, so that said rod-shaped means is received in said passage with clearance.

4. A supporting device as defined in claim 1; and further comprising cooperating screwthreads provided on said leading end portion of said supporting sleeve and on said expansion element, respectively, for permitting releasable connection of the latter with the former.

5. A supporting device for fractured tubular bones which have a longitudinally extending curved interior cavity, comprising an elongated supporting sleeve having a leading and a trailing end portion and being curved in at least substantial conformance with said cavity, said supporting sleeve being provided with a curved longitudinal passage having a widened section at said trailing end portion; an expansion element at said leading end portion located forwardly thereof; expander means associated with said expansion element, said expander means including rod-shaped means extending through saidpassage between said end portions and adapted to expand said element in response to axial displacement towards said trailing end portion, and displacing means at least partially received in said widened section in engagement with said rod-shaped means and operative for effecting displacement thereof only axially of said supporting sleeve in direction towards said trailing end portion, said displacing means being a hollow internally threaded cap sleeve having an open end facing away from said leading end portion, and said rod-shaped means having external screw threads which mesh with the internal threads of said cap sleeve, said rod-shaped means having a length such that a terminal portion thereof extends outwardly through said open end when said rod-shaped means has been axially displaced by a distance requisite for expanding said expansion element; and a cap unit configurated for threading engagement with said terminal portion and having a head adapted to bear against said bone.

6. A supporting device as defined in claim 5; further comprising an annular member dimensioned to externally surround said trailing end portion of said supporting sleeve; and cooperating rotation-preventing portions provided on said trailing end portion and on said annular member, respectively, said cap unit being configurated for engaging said annular member and retaining it against movement axially of said sleeve.

7. A supporting device as defined in claim 6, said annular member having one axial end facing towards said leading end portion of said sleeve; and wherein said rotation-preventing portions comprise axially extending slots provided in said annular member extending rearwardly from said one axial end thereof, and axially extending ribs provided on said trailing end portion of said sleeve and received in the respective slots.

8. A supporting device as defined in claim 6, said annular member having an axial end facing away from said leading end portion; and further comprising an annular component having a first portion dimensioned to be receivable in said annular member at said axial end thereof, and a second portion dimensioned to at least in part overlie an axial endface of said annular member at said axial end thereof.

9. A supporting device as defined in claim 8; further comprising a hooked portion provided on one of said annular member and annular component and being adapted to hook onto the edge of a hole which is provided in said bone for insertion of said sleeve into said cavity.

10. A supporting device as defined in claim 9, wherein said hooked portion is provided on said annular member.

11. A supporting device as defined in claim 9, wherein said hooked portion is provided on said annular component.

12. A supporting device for fractured tubular bones which have a longitudinally extending curved interior cavity, comprising an elongated supportingsleeve having a leading and a trailing end portion and being curved in at least substantial conformance with said cavity, said supporting sleeve being provided with a curved longitudinal passage having a widened section at said trailing end portion; an expansion element at said leading end portion located forwardly thereof; expander means associated with said expansion element, said expander means including rod-shaped means extending through said passage between said end portions and adapted to expand said element in response to axial displacement towards said trailing end portion, and displacing means at least partially received in said widened section in engagement with said rod-shaped means and operative for effecting displacement thereof only axially of said supporting sleeve in direction towards said trailing end portion, said displacing means being a hollow internally threaded cap sleeve having an open end facing away from said leading end portion, and said rod-shaped means having external screw threads which mesh with the internal threads of said cap sleeve, said rod-shaped means having a length such that a terminal portion thereof extends outwardly on said extension rod and in said bore. 

1. A supporting device for fractured tubular bones which have a longitudinally extending curved interior cavity, comprising an elongated supporting sleeve having a leading and a trailing end portion and being curved in at least substantial conformance with said cavity, said supporting sleeve being provided with a curved longitudinal passage having a widened section at said trailing end portion; an expansion element at said leading end portion located forwardly thereof; expander means associated with said expansion element, said expander means including rod-shaped means extending through said passage between said end portions and adapted to expand said element in response to axial displacement towards said trailing end portion, and displacing means at least partially received in said widened section in engagement with said rod-shaped means and operative for effecting displacement thereof only axially of said supporting sleeve in direction towards said trailing end portion, said displacing means being a hollow internally threaded cap sleeve having an open end facing away from said leading end portion, and said rod-shaped means having external screw threads which mesh with the internal threads of said cap sleeve; and a cap screw having external threads dimensioned to mesh with the internal threads of said cap sleeve.
 2. A supporting device as defined in claims 1, said expander means further comprising an expander portion provided on said rod-shaped means and engaging said expansion element for effecting expansion of the same in response to said axial displacement of said rod-shaped means in direction towards said trailing end portion.
 3. A supporting device as defined in claim 1, said rod-shaped means having an outer diameter which is substantially smaller than the inner diameter of said passage, so that said rod-shaped means is received in said passage with clearance.
 4. A supporting device as defined in claim 1; and further comprising cooperating screwthreads provided on said leading end portion of said sUpporting sleeve and on said expansion element, respectively, for permitting releasable connection of the latter with the former.
 5. A supporting device for fractured tubular bones which have a longitudinally extending curved interior cavity, comprising an elongated supporting sleeve having a leading and a trailing end portion and being curved in at least substantial conformance with said cavity, said supporting sleeve being provided with a curved longitudinal passage having a widened section at said trailing end portion; an expansion element at said leading end portion located forwardly thereof; expander means associated with said expansion element, said expander means including rod-shaped means extending through said passage between said end portions and adapted to expand said element in response to axial displacement towards said trailing end portion, and displacing means at least partially received in said widened section in engagement with said rod-shaped means and operative for effecting displacement thereof only axially of said supporting sleeve in direction towards said trailing end portion, said displacing means being a hollow internally threaded cap sleeve having an open end facing away from said leading end portion, and said rod-shaped means having external screw threads which mesh with the internal threads of said cap sleeve, said rod-shaped means having a length such that a terminal portion thereof extends outwardly through said open end when said rod-shaped means has been axially displaced by a distance requisite for expanding said expansion element; and a cap unit configurated for threading engagement with said terminal portion and having a head adapted to bear against said bone.
 6. A supporting device as defined in claim 5; further comprising an annular member dimensioned to externally surround said trailing end portion of said supporting sleeve; and cooperating rotation-preventing portions provided on said trailing end portion and on said annular member, respectively, said cap unit being configurated for engaging said annular member and retaining it against movement axially of said sleeve.
 7. A supporting device as defined in claim 6, said annular member having one axial end facing towards said leading end portion of said sleeve; and wherein said rotation-preventing portions comprise axially extending slots provided in said annular member extending rearwardly from said one axial end thereof, and axially extending ribs provided on said trailing end portion of said sleeve and received in the respective slots.
 8. A supporting device as defined in claim 6, said annular member having an axial end facing away from said leading end portion; and further comprising an annular component having a first portion dimensioned to be receivable in said annular member at said axial end thereof, and a second portion dimensioned to at least in part overlie an axial endface of said annular member at said axial end thereof.
 9. A supporting device as defined in claim 8; further comprising a hooked portion provided on one of said annular member and annular component and being adapted to hook onto the edge of a hole which is provided in said bone for insertion of said sleeve into said cavity.
 10. A supporting device as defined in claim 9, wherein said hooked portion is provided on said annular member.
 11. A supporting device as defined in claim 9, wherein said hooked portion is provided on said annular component.
 12. A supporting device for fractured tubular bones which have a longitudinally extending curved interior cavity, comprising an elongated supporting sleeve having a leading and a trailing end portion and being curved in at least substantial conformance with said cavity, said supporting sleeve being provided with a curved longitudinal passage having a widened section at said trailing end portion; an expansion element at said leading end portion located forwardly thereof; expander means associated with said expansion element, said expandeR means including rod-shaped means extending through said passage between said end portions and adapted to expand said element in response to axial displacement towards said trailing end portion, and displacing means at least partially received in said widened section in engagement with said rod-shaped means and operative for effecting displacement thereof only axially of said supporting sleeve in direction towards said trailing end portion, said displacing means being a hollow internally threaded cap sleeve having an open end facing away from said leading end portion, and said rod-shaped means having external screw threads which mesh with the internal threads of said cap sleeve, said rod-shaped means having a length such that a terminal portion thereof extends outwardly through said open end when said rod-shaped means has been axially displaced by a distance requisite for expanding said expansion element; and an extension rod having an outer diameter smaller than the root diameter of said external screw threads, a bore in an axial end face of said terminal portion, and cooperating threads on said extension rod and in said bore. 